The introduction of Device-to-Device (D2D) communication technology provides technical support to improve spectrum efficiency, improve system throughput, reduce the energy consumption of a user device (also referred to as user equipment), and reduce the operating costs of operators. Research on the D2D communication technology has been launched in the current 3GPP network, in which a variety of application scenarios of the D2D communication technology has been defined. Current network side D2D communication technology research focus on methods for establishing a D2D communication network in the physical layer, for example, how to establish a D2D communication network between two user devices.